Deiglmayr Johannes, Aymar Mireille, Wester Roland, Weidemüller Matthias, Dulieu Olivier
Physikalisches Institut, Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany.
J Chem Phys. 2008 Aug 14;129(6):064309. doi: 10.1063/1.2960624.
The rapid development of experimental techniques to produce ultracold alkali molecules opens the ways to manipulate them and to control their dynamics using external electric fields. A prerequisite quantity for such studies is the knowledge of their static dipole polarizability. In this paper, we computed the variations with internuclear distance and with vibrational index of the static dipole polarizability components of all homonuclear alkali dimers including Fr(2), and of all heteronuclear alkali dimers involving Li to Cs, in their electronic ground state and in their lowest triplet state. We use the same quantum chemistry approach as in our work on dipole moments [Aymar and Dulieu, J. Chem. Phys. 122, 204302 (2005)], based on pseudopotentials for atomic core representation, Gaussian basis sets, and effective potentials for core polarization. Polarizabilities are extracted from electronic energies using the finite-field method. For the heaviest species Rb(2), Cs(2), and Fr(2) and for all heteronuclear alkali dimers, such results are presented for the first time. The accuracy of our results on atomic and molecular static dipole polarizabilities is discussed by comparing our values with the few available experimental data and elaborate calculations. We found that for all alkali pairs, the parallel and perpendicular components of the ground state polarizabilities at the equilibrium distance R(e) scale as (R(e))(3), which can be related to a simple electrostatic model of an ellipsoidal charge distribution. Prospects for possible alignment and orientation effects with these molecules in forthcoming experiments are discussed.
用于产生超冷碱分子的实验技术的迅速发展，为操纵这些分子并利用外部电场控制其动力学开辟了道路。此类研究的一个先决条件是了解它们的静态偶极极化率。在本文中，我们计算了包括Fr₂在内的所有同核碱二聚体以及涉及从Li到Cs的所有异核碱二聚体在其电子基态和最低三重态下，静态偶极极化率分量随核间距和振动指数的变化。我们采用了与我们在研究偶极矩时相同的量子化学方法[Aymar和Dulieu，《化学物理杂志》122，204302(2005)]，该方法基于用于原子核表示的赝势、高斯基组以及用于核极化的有效势。极化率是使用有限场方法从电子能量中提取的。对于最重的物种Rb₂、Cs₂和Fr₂以及所有异核碱二聚体，此类结果是首次给出。通过将我们的值与少数可用的实验数据以及精细计算进行比较，讨论了我们关于原子和分子静态偶极极化率结果的准确性。我们发现，对于所有碱对，平衡距离R(e)处基态极化率的平行和垂直分量按(R(e))³缩放，这可以与一个简单的椭球形电荷分布静电模型相关联。讨论了在即将进行的实验中使用这些分子可能产生的取向和排列效应的前景。
